The invention relates to electric vehicles; and more particularly, to circuitry for providing recovery of electrical energy in an electric vehicle when braking.
Electric vehicles are, of course, old and well known. For many years, delivery vehicles used in cities were electric vehicles. In the late 1930's to more recent times, the electric vehicle gave way to the internal combustion engine driven vehicle. One major reason why electric vehicles were abandoned in favor of internal combustion engined vehicles was the limited range of electric vehicles between battery recharging. In addition, gasoline and diesel fuels were plentiful and inexpensive.
Due to the recent oil shortage and the increased price of crude oil, the interest in electric vehicles has been renewed. However, even the modern day electric vehicles can only provide a limited number of hours of operation before the batteries have to be recharged. These batteries are generally charged at the garage or maintenance facility. Some electric vehicles are provided with on-board chargers.
An example of the modern day electric vehicle with an on-board battery charger is the U.S. Post Office Urban Delivery electric vehicle which is a modified Jeep. The electric vehicle propulsion system of the postal vehicle utilizes a separate propulsion and on-board charging means for the battery. With separate on-board charging means for energy recuperation, there is a practical trade-off between weight of the charging means and energy recuperation which severely limits the on board energy recuperation in these Post Office electric vehicles. Thus, the drive range of these electrical vehicles between base recharges is primarily governed by the capacity of the batteries, and the drive range extension provided by the on board recuperation means is minimal.
This invention provides a means for recovering energy in electric vehicles when braking and utilizes the recovered energy for rejuvination purpose without significant overall weight increase. Without a limiting tradeoff to consider it will be appreciated that the circuitry of this invention extends the drive range between recharges of the batteries of an electric vehicle.